The present invention relates generally to optical alignment systems and more specifically to an optical system for detecting misalignment of the optical components of high energy laser systems.
The efficient operation of high energy laser systems requires first that the optical components comprising the optical resonant cavity of the laser and the reflective elements comprising the optical train, through which the high energy laser beam output is coupled and directed toward a target, be in substantially perfect optical alignment. Precision alignment of the optics of a high energy laser is particularly critical since even slight misalignment can result in severe reduction in beam output power or undesirable multimode beam characteristics. Further, damage to the optical components or other structures comprising the high energy laser system may often result if the high energy beam generated by the system itself is used in an attempt to align the optical components of the high energy laser system. Therefore, a collimated light beam from an external source, such as a low power helium neon (HeNe) laser, has conventionally been used as a reference beam, directed into the optical path of the high energy laser system, to verify the alignment of the optical components comprising the high energy laser system.
Existing manual alignment systems or methods generally involve one or more of the following: (1) temporary removal of an optical component (such as a mirror) from the high energy laser optical train to provide access for the alignment beam to align the remaining components, followed by replacement of the temporarily removed component and alignment thereof using high energy cavity generated radiation; (2) use of an apertured optical component in the optical train of the high energy system to provide access of the alignment beam to the high energy optical path; (3) use of an alignment beam directed into the high energy beam path and the resonant cavity parallel to and offset from the optical axis of the high energy beam.
The principal disadvantages of these methods include lack of simultaneous alignment of all of the optical components comprising the high energy beam optical train prior to high energy laser operation, undesirable modification to optical train components to accommodate the alignment beam, and relative inaccessibility of the optical path for routine or periodic pre-run alignment checks.
Certain automatic alignment systems described previously are extremely accurate but generally comprise complicated and expensive components for their implementation and use. For example, such systems may include computer controlled mirror mounts and utilize a low power laser alignment beam to actuate the alignment via closed loop detectors (position sensors); such systems may further require high power grating rhomb mirrors to perform low power sampling for alignment purposes. Since the autoalignment systems typically do not respond immediately during the initial transient phase of a laser experiment, damage to external elements may be experienced during the time the autoalignment system is attempting to align the high energy laser optical components. In extreme cases, the external laser optical train may be so far out of co-alignment with the internal laser cavity optical components that the resulting laser mode is unsuitable for continued testing. Such an unknown state of laser cavity and optical train co-alignment may result in expensive downtime for the laser system, damage to the laser system components, and reduced confidence that the entire optical system is properly aligned.
The alignment system of the present invention interfaces with the optical path of a high energy laser system at any convenient access thereto, provides rapid and accurate determination of any misalignment in the entire optical system of the high energy laser system, and facilitates the precision alignment thereof without the necessity for operation of the high energy system or for modification of any of the components thereof. Only an access to the high energy beam path is required. The alignment system of the present invention may be packaged as a self-contained system, modularized, and used on a wide variety of laser systems. Alignment may be accomplished in a desirably short time with a high degree of precision. The invention may be particularly useful in the alignment of industrial laser welders, such as the CO.sub.2 type.
It is, therefore, a principal object of the present invention to provide an improved optical alignment system.
It is a further object of the invention to provide an optical alignment system for detecting misalignment of the optics of a high energy laser generating system.
It is a further object of the invention to provide an optical alignment system for a high energy laser system which is characterized by its simplicity, high precision and reliability.
These and other objects of the present invention will become apparent as the detailed description of certain representative embodiments thereof proceeds.